Colorless and Transparent Polyimide Microporous Film with Excellent Physicochemical Property

4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA) as a dianhydride and bis(3-aminophenyl) sulfone (APS) and bis(3-amino-4-hydroxyphenyl) sulfone (APS-OH) as diamines were used to synthesize two types of poly(amic acid) (PAA). Varying amounts (0–5.0 wt%) of water-soluble poly(vinyl alcohol) (PVA) were mixed with PAA, and the resulting blend was heat-treated at different stages to obtain the colorless and transparent polyimide (CPI) blend films. The synthesized blended film completely removed water-soluble PVA in water. The possibility as a porous membrane according to the pore size varied according to the amount of PVA was investigated. The dispersibility and compatibility of CPI containing APS-OH monomer were higher than those of the APS monomer. This could be attributed to the hydrogen-bonding interactions between the CPI main chains and PVA. Scanning electron microscopy was conducted to characterize the material. The results revealed that the pore size of the CPI blend film increased as the PVA concentration increased. It was confirmed that uniform pores of μm-size were observed in CPI. The thermal stabilities, morphologies, optical properties, and solubilities of two CPIs obtained using APS and APS-OH monomers were investigated and their properties were compared with each other.

Effects of Ozone Treatment on the Storage Quality of Post-Harvest Tomato

Effects of ozone treatment on the storage quality of post-harvest tomato were investigated. The tomatoes packed in microporous film were treated with 4.29 mg·(m3)−1, 8.57 mg·(m3)−1, 12.86 mg·(m3)−1 and 17.14 mg·(m3)−1 ozone gas for 1 h at 0℃. The firmness, ethylene, vitamin C (VC), malonaldehyde (MDA), ascorbate peroxidase (APX), peroxidase (POD) and aromatic compounds were tested to determine the proper ozone concentrations. Compared with other treatments, 17.14 mg·(m3)−1 ozone could maintain the firmness of tomato, depress ethylene, keep the content of VC and aromatic compounds, and inhibit the accumulation of MDA and activity of POD and APX, which had a good fresh-keeping effect on tomato.

High-performance nickel manganese ferrite/oxidized graphene composites as flexible and binder-free anodes for Li-ion batteries

The obtained binder-free and flexible free-standing Ni0.5Mn0.5Fe2O4/oxidized graphene (NMFO/OGP) and NMFO/OGP coated on polypropylene microporous film exhibited good electrochemical performance.